W. Skey. — On the Evolution of Sulphur from Carbon. 395 



reality a similar position to tbat which I have shown gold and platinum 

 sustain to this substance. 



Now, if all this appears correct — and the great probability is conceded that 

 absorption of sulphuretted hydrogen by charcoal is a chemical one, resulting in 

 the formation of sulphide of carbon — then I maintain that the evolution of this 

 gas from the negative pole of the battery, as described by Mr. Highton, is, 

 upon analogical grounds alone, precisely one of the effects we should antici- 

 pate on becoming acquainted with the general behaviour of metallic sulphides 

 occupying the negative end of a galvanic battery ; for, as before stated, I have 

 proved such sulphides evolve sulphuretted hydrogen under these circum- 

 stances, and by a process which appears very simple, hydrogen (for which as 

 to its chemical might Mr. Highton exhibits such great faith) being in this 

 case, I believe, the agent, through the intense desire of which for consum- 

 mating chemical alliances with approved substances, these compounds owe 

 their origin in the instances cited. 



However this may be brought about the gas is certainly generated when 

 such sulphides are paired with more positive substances in sulphuric acid, and 

 it proceeds from these sulphides. When, therefore, we refuse to allow that at 

 least a portion of the sulphuretted hydrogen obtained by Mr. Highton from 

 his carbon plate is derived and produced in this manner, we are breaking 

 through very strong analogy indeed ; and, what is even unphilosophical, we are 

 spurning analogies of this character to embrace (in the case of the alleged 

 decomposition of sulphuric acid by nascent hydrogen) a hypothesis which I 

 submit, with all deference to Mr. Highton, is not yet supported either upon 

 analogical or experimental evidence. 



In conclusion, what I conceive as legitimate deductions from long known 

 facts, obvious analogies, and the results of experimental evidence, collectively 

 support the view that the H2S observed, first by myself and next by Mr. 

 Highton, to escape from a battery in action, of which graphite is the negative 

 pole — is not a product of the decomposition of either sulphuric acid or any 

 ferruginous sulphide, as has been maintained, but is liberated as to its sulphur 

 from combination with the carbon of these batteries — this substance being, 

 from its well-known proclivities, certain to be in a sulphurized state when 

 used by Mr. Highton. 



I have only to add that, even were sulphur only present in graphitic 

 carbon as a component part of sulphurous acid, the effects as observed by Mr. 

 Highton would be precisely the same as those he has stated j so that before it 

 would be correct to assert the decomposition of sulphuric acid by nascent 

 hydrogen in contact with carbon, we should not only be certain that sulphides 

 are absent but sulphites or sulphurous acid also. 



